HB wrote:Timing traditionally begins when the brew pressure is applied and the extraction lasts 20-30 seconds. Most commercial espresso machines have rotary pumps and they pressurize nearly instantaneously; the espresso beads on the bottom of the basket in barely 3 seconds. Most home espresso machines have vibe pumps and require 5-7 seconds before the first drops appear on the bottom of the basket. That may explain the differences you have read.

That said, once you get beyond the beginner stage, Jim's advice early in this thread is best:

Understood. Well assuming I like the body, taste and look of my espresso, but I want more volume how do I do that? I imagine maybe a different OPV setting? (i've recently dialed it down from 10.5 to 9.5 bars).

Right now I am getting about 2 oz before my shot starts to blonde, and if I try grinding coarser to get more volume, the espresso gets to "thin". (my grind (MACAP), tamp (Auto 30# tamper), PID temperature are all constant)

AUSTINrob wrote:Understood. Well assuming I like the body, taste and look of my espresso, but I want more volume how do I do that? I imagine maybe a different OPV setting? (i've recently dialed it down from 10.5 to 9.5 bars).

Right now I am getting about 2 oz before my shot starts to blonde, and if I try grinding coarser to get more volume, the espresso gets to "thin". (my grind (MACAP), tamp (Auto 30# tamper), PID temperature are all constant)

If you are happy with your espresso, why change? Back to back doubles ("quad-shot"?) would be my humble solution. Your other options are to try more coffee in combination with different and/or larger baskets.

HB wrote:Timing traditionally begins when the brew pressure is applied

Does 'brew pressure' mean pre-infusion, too? I never got very clear on that in the earlier discussion.

HB wrote:That said, once you get beyond the beginner stage, Jim's advice early in this thread is best:

I dunno, the stopwatch is a useful tool, when applied correctly. I start the watch at thirty seconds (actually, it's the timer on my microwave) and then go to the machine and start the pull. Once it's where I want to stop it, it is very satisfying to be reaching for the button to stop it, and then hear the timer go off. Of course, I usually check the timer as I turn of the machine, just to see where I am. It is a great indicator of how things are progressing.
I would never stop a pull based on a timer. I look at the shot. I've had some fifty second triple ristretti that have been out of this world. Sweet, great mouthfeel, warm and buttery with nutty.... er... I'll be right back...
'Kay, where was I? Oh yeah! Don't let the clock dictate, but you can use it as a measuring tool.

Use a timer that counts up from 0:00, stopping the shot on color.
As PSYD says, fabulous shots occur in the 40's.

Two advantages of count up :
1 - No annoying beep. It's bloody annoying in a busy shop that uses timers to hear the incessant beep.
2 - Times the intershot interval. Over time, can be used to gauge how long a flush is required on an HX.

cafeIKE wrote:1 - No annoying beep. It's bloody annoying in a busy shop that uses timers to hear the incessant beep.

Shop? How many HB'ers are pulling shots in their shops? If anyone tells em that the beep is annoying them, I simply turn, get all red in the face, threaten them with the naked PF, and scream (at the top of my lungs) "NO ESPRESSO FOR YOU! Come back, one year!" ; >

Psyd wrote:Does 'brew pressure' mean pre-infusion, too? I never got very clear on that in the earlier discussion.

From Lattice Boltzmann model for coffee percolation:

To prepare a 'good' espresso is not an easy task. Many variables can affect the quality of the coffee, such as water pressure and temperature, the amount of ground coffee, how hard it is pressed and (not less important) the practice of the barman. Evidently some of these parameters cannot be controlled in a scientific way, but, for those that can, a few optimal conditions have been empirically determined:

water temperature: inside the machine it should be about 88°C;
pressure: it should be a function of time with profile as shown in Fig. 1;
quantity of coffee: 7 g;
duration: the whole process should take 30 seconds;
production: at the end, we should have about 25 ml of coffee in the cup.

Bottom Line : If it tastes well, do it.

88°C ? That's a bit low ...

Kim

micki wrote:88°C ? That's a bit low ...

"about 88°C" could be a poor translation from "at least 88°C"
IIRC, generally accepted range is 88° to 96°C / 190° to 205°F